Ramjet Bleed-Air Combustion for Continuous Turbine Accessory Power
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Solution Overview
Problem
Aircraft propulsion systems with combined gas turbine and ramjet engines face challenges in maintaining the operation of the gas turbine engine during high-speed flights, as they typically shut down the gas turbine engine once the ramjet engine is ignited, necessitating reactivation at lower speeds, which disrupts the operation of accessories like generators and environmental systems.
Innovation Solution
A propulsion system design that allows the gas turbine engine to remain operational by diverting ramjet bleed air to the combustor, mixing it with fuel for combustion, and using the turbine section to drive accessories, even during high-speed flights by restricting inlet airflow and using ramjet bleed air to maintain turbine engine operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the gas turbine engine is shut down during high-speed flight when the ramjet engine is operational, then the ramjet engine can provide efficient high-speed propulsion, but the gas turbine engine accessories and environmental systems lose their power source and must be reactivated when speed decreases
Solution Approach 1:
The patent introduces an intermediary airflow path that diverts ramjet bleed air to the gas turbine combustor. This mediator airflow allows the gas turbine engine to remain operational during high-speed flight without requiring its own inlet airflow, thus maintaining power to accessories and environmental systems while the ramjet provides propulsion.
Solution Approach 2:
The patent makes the gas turbine engine multi-functional by allowing it to operate in two modes: (1) as a primary propulsion engine at low speeds with its own inlet airflow, and (2) as an accessory power source at high speeds using ramjet bleed air. This universality resolves the contradiction by enabling the gas turbine to serve both propulsion and accessory power needs across different flight regimes.
2Reliability
If the gas turbine engine remains operational during high-speed flight by diverting ramjet bleed air to the combustor, then accessories and environmental systems continue to receive power, but inlet airflow to the gas turbine must be restricted
Solution Approach 1:
The patent employs dynamic airflow control mechanisms including movable inlet doors and bleed air valves that can adjust their positions based on flight conditions. These dynamic components allow the system to transition between low-speed and high-speed operating modes, managing airflow distribution between the gas turbine inlet and ramjet bleed air passages as needed.
Solution Approach 2:
The patent implements preliminary action by pre-positioning airflow control components (inlet doors, bleed valves) in appropriate configurations before mode transitions occur. The system anticipates flight regime changes and prepares the airflow paths in advance, ensuring smooth transitions between gas turbine-only operation and combined gas turbine-ramjet operation.
3Productivity
If the gas turbine engine is reactivated when airspeed decreases from high-speed flight, then it can resume primary propulsion, but the repeated shutdown and reactivation disrupts accessory operation and reduces system reliability
Solution Approach 1:
The patent ensures continuous useful action by maintaining the gas turbine engine in an operational state throughout high-speed flight. By keeping the combustor and turbine spinning using ramjet bleed air, the system avoids complete shutdown and reactivation cycles, thereby eliminating the time loss and reliability disruptions associated with repeated engine restarts while transitioning between flight regimes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables continuous operation of the gas turbine engine accessories and environmental systems during high-speed flights, ensuring reliable power and system functionality without the need for repeated engine reactivation.
Implementation Method 1
mixing it with fuel for combustion
Data Source
AI summary
A propulsion system includes a ramjet engine and a turbine engine configured for multimode operation. The turbine engine includes a compressor section, a combustor, and a turbine section, while the ramjet engine includes a ramjet bleed air passage. A combustor inlet flow control device positioned at an outlet end of the compressor section includes a bleed valve having a ramjet bleed air inlet, a compressor bleed air outlet, and a flow control element rotatable between two positions. In a first position, the flow control device directs compressor bleed air to the turbine engine combustor. In a second position, the flow control device restricts compressor air and directs ramjet bleed air to the combustor. This configuration enables continued operation of the turbine section to drive engine accessories using ramjet-supplied air during high-speed flight when the compressor is inactive. A corresponding method for regulating airflow based on operational state is also disclosed.